Compressor

ABSTRACT

A compressor has a housing, which supports a rotary shaft, and a crank chamber. A swash plate is accommodated in the crank chamber. The compressor has an oil chamber located in the housing near a front end portion of the rotary shaft. The oil chamber has an inlet and an outlet. The outlet connects to the suction pressure zone. Either lubricant oil that is separated from refrigerant gas or refrigerant gas in the suction pressure zone flows into the oil chamber from the inlet and flows out from the outlet to the suction pressure zone. A seal mechanism seals the oil chamber. A seal seals between the oil chamber and the crank chamber. This permits an inclination angle of the swash plate to control accurately and smoothly while lubricating the seal mechanism optimally.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to compressors provided with a seal mechanism that prevents refrigerant gas from leaking from a housing to the exterior of the housing along a rotary shaft.

[0002]FIG. 7 shows a prior art variable displacement compressor, which is described in Japanese Unexamined Patent Publication No. 11-241681. The compressor includes a housing that has a front housing member 71, a cylinder block 72, and a rear housing member 73. The front housing member 71 is securely coupled with the cylinder block 72, and the cylinder block 72 is securely coupled with the rear housing member 73. The housing rotationally supports a rotary shaft 74 through a pair of radial bearings, or a first radial bearing 75 and a second radial bearing 76. A front end of the rotary shaft 74 projects from the front housing member 71. A shaft seal 78 is fitted around the front end of the rotary shaft 74, thus preventing refrigerant gas from leaking from a crank chamber 77 to the exterior of the compressor. The refrigerant gas contains lubricant oil in the form of mist. The lubricant oil lubricates movable portions of the radial bearings 75, 76, which slide along the rotary shaft 74.

[0003] A depressurizing passage 79 is formed in the rotary shaft 74. An inlet 79 a of the depressurizing passage 79 is formed in the rotary shaft 74 at a position between the first radial bearing 75 and the shaft seal 78. The inlet 79 a extends in a radial direction of the rotary shaft 74 and is connected to an oil chamber 80. An outlet 79 b of the depressurizing passage 79 forms an opening in a rear end of the rotary shaft 74. A fan 81 is attached to the rear end of the rotary shaft 74. The fan 81 rotates integrally with the rotary shaft 74, thus sending refrigerant gas from the depressurizing passage 79 to the exterior of the depressurizing passage 79 through the outlet 79 b. The refrigerant gas then flows to the crank chamber 77 through a clearance formed by the second radial bearing 76.

[0004] The oil chamber 80 is connected to the crank chamber 77 through a clearance formed by the first radial bearing 75 and a clearance formed by a thrust bearing 82. Refrigerant gas thus flows from the crank chamber 77 to the oil chamber 80 through the clearances.

[0005] As shown in FIG. 7, the fan 81 rotates to draw some refrigerant gas from the crank chamber 77 to the depressurizing passage 79 through the clearance of the first radial bearing 75 and the clearance of the thrust bearing 82. The refrigerant gas is then discharged from the depressurizing passage 79. Afterward, some of the refrigerant gas is re-circulated to the crank chamber 77 through the clearance of the second radial bearing 76. This sufficiently lubricates the first and second radial bearings 75, 76 and the shaft seal 78. However, the fan 81 complicates the configuration of the compressor.

[0006] Further, some refrigerant gas flows from the crank chamber 77 to the oil chamber 80 through a hole in which the rotary shaft 74 is received and the clearance formed by the first radial bearing 75. That is, the hole and the clearance connect the crank chamber 77 to the oil chamber 80.

[0007] The variable displacement compressor includes a drive plate 83. The drive plate 83 is inclined at an angle altered in relation to the pressure in the crank chamber 77 and the pressure in a suction chamber, or suction pressure, which both act on a piston 84. The pressure in the crank chamber 77 is thus adjusted to change the stroke of the piston 84. This varies the compressor displacement. However, if the crank chamber 77 is connected to the oil chamber 80, the compressor displacement is not varied as desired. Further, if carbon dioxide is used as refrigerant, the pressure in the compressor is greatly increased as compared to a case in which chlorofluorocarbon is used as refrigerant. This increases the load that acts on the first and second radial bearings 75, 76 and the shaft seal 78, thus requiring an increased lubrication.

[0008] Japanese Unexamined Patent Publication No. 6-66252 describes a swash plate type variable displacement compressor with double-headed pistons. The compressor includes a seal mechanism that is located near a front end of the compressor. When a front side of a double-headed piston does not compress refrigerant gas, which is referred to as “a decompressing state”, lubricant oil must be supplied to the seal mechanism. Thus, in this state, refrigerant gas flows from the suction chamber to a chamber that accommodates the seal mechanism, thus lubricating the seal mechanism.

[0009] However, this structure is applicable only to swash plate type variable displacement compressors that have double-headed pistons. Thus, the structure is inapplicable to single-headed piston type variable displacement compressors.

BRIEF SUMMARY OF THE INVENTION

[0010] Accordingly, it is an objective of the present invention to provide a single-headed piston type compressor that controls inclination angle of a drive plate accurately and smoothly while lubricating a seal mechanism optimally.

[0011] To achieve the above objective, the present invention provides following a compressor. The compressor has a housing, which has a suction pressure zone, and a crank chamber. A cylinder bore is formed in the housing. A rotary shaft has a front end portion and a rear end portion. The rotary shaft is supported by the housing such that the front end portion of the rotary shaft protrudes from the housing. A piston is accommodated in the cylinder bore. A swash plate is accommodated in the crank chamber and is connected to the piston such that rotation of the rotary shaft is converted to reciprocation of the piston. An oil chamber is located in the housing near the front end portion of the rotary shaft. The oil chamber has an inlet and an outlet. The outlet connects to the suction pressure zone. Either lubricant oil that is separated from refrigerant gas or refrigerant gas in the suction pressure zone flows into the oil chamber from the inlet and flows out from the outlet to the suction pressure zone. A seal mechanism seals the oil chamber. A seal seals between the oil chamber and the crank chamber.

[0012] Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

[0014]FIG. 1 is a cross-sectional view showing a compressor of a first embodiment according to the present invention;

[0015]FIG. 2 is a cross-sectional view showing a compressor of a second embodiment according to the present invention;

[0016]FIG. 3 is a cross-sectional view showing a compressor of a third embodiment according to the present invention;

[0017]FIG. 4 is a cross-sectional view showing a compressor of a fourth embodiment according to the present invention;

[0018]FIG. 5 is a cross-sectional view showing a compressor of a fifth embodiment according to the present invention;

[0019]FIG. 6(a) is a cross-sectional view showing a ring seal of a sixth embodiment according to the present invention;

[0020]FIG. 6(b) is a cross-sectional view showing a ring seal of a seventh embodiment according to the present invention;

[0021]FIG. 6(c) is a cross-sectional view showing a ring seal of an eighth embodiment according to the present invention; and

[0022]FIG. 7 is a cross-sectional view showing a prior art compressor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] A compressor of a first embodiment according to the present invention will now be described with reference to FIG. 1.

[0024] As shown in FIG. 1, the compressor includes a housing that has a cylinder block 11, a front housing member 12, and a rear housing member 13. The front housing member 12 and the rear housing member 13 are coupled to the cylinder block 11 through a plurality of bolts (only one is shown). The front housing member 12 and the cylinder block 11 form a crank chamber 12 a. The cylinder block 11 and the front housing member 12 rotationally support a rotary shaft 14 through a first radial bearing 15 and a second radial bearing 16. More specifically, the first radial bearing 15 is received in a through hole 12 b that extends through the front housing member 12, thus supporting the rotary shaft 14. The second radial bearing 16 is received in a through hole that extends through the cylinder block 11, thus supporting the rotary shaft 14. A circular lug plate 17 is secured to the rotary shaft 14 in the crank chamber 12 a. A pair of support arms 17 a project from an outer circumferential portion of the lug plate 17. A guide hole 17 b extends through each support arm 17 a.

[0025] The rotary shaft 14 supports a swash plate 18, which functions as a drive plate. The swash plate 18 inclines with respect to the rotary shaft 14 and axially slides along the rotary shaft 14. A connector 18 a projects from the swash plate 18. A pair of guide pins 19 are attached to a distal end of the connector 18 a.

[0026] Each guide pin 19 is fitted in the associated guide hole 17 b. The lug plate 17 guides the swash plate 18 to slide along the rotary shaft 14 through the guide pins 19 fitted in the associated guide holes 17 b. In other words, the swash plate 18 is allowed to incline with respect to the rotary shaft 14, axially move along the rotary shaft 14, and rotate integrally with the rotary shaft 14 by the fitting contact between the guide pins 19 and the guide holes 17 b, and between the rotary shaft 14 and the swash plate 18.

[0027] A plurality of cylinder bores 11 a are formed in the cylinder block 11. A single-headed piston 20 is accommodated in each cylinder bore 11 a. Each piston 20 forms a compression chamber 11 b in the associated cylinder bore 11 a. A head 20 a of each piston 20 is operationally connected to the swash plate 18 through a pair of shoes 21. When the swash plate 18 rotates in the crank chamber 12 a, the rotation of the swash plate 18 is converted to reciprocation of each piston 20 through the associated shoes 21. The piston 20 thus moves in the associated cylinder bore 11 a.

[0028] A suction chamber 13 a and a discharge chamber 13 b are formed in the rear housing member 13. A valve plate assembly 50 is located between the cylinder block 11 and the rear housing member 13. The valve plate assembly 50 includes a main plate 22, a first sub-plate 23, and a second sub-plate 24. A plurality of suction ports 22 a and a plurality of discharge ports 22 b are formed in the main plate 22 at positions corresponding to the associated cylinder bores 11 a. Each suction port 22 a is selectively opened and closed by a corresponding suction valve 23 a that is formed in the first sub-plate 23. Each discharge port 22 b is selectively opened and closed by a corresponding discharge valve 24 a that is formed in the second sub-plate 24. The opening size of the discharge valve 24 a is restricted by a retainer 24 b.

[0029] When each piston 20 moves from a bottom dead center to a top dead center, refrigerant gas flows from the compression chamber 11 b, which is formed in the associated cylinder bore 11 a, to the discharge chamber 13 b through the associated discharge port 22 b that is opened by the discharge valve 24 a. In contrast, when each piston 20 moves from a top dead center to a bottom dead center, refrigerant gas flows from the suction chamber 13 a to the compression chamber 11 b through the associated suction port 22 a that is opened by the suction valve 23 a.

[0030] The stroke of each piston 20 is altered in accordance with the difference between the pressure in the crank chamber 12 a and the pressure in the compression chamber 11 b, or the difference between the pressure in the crank chamber 12 a and the suction pressure of the compressor. In other words, the inclination angle of the swash plate 18 is altered in relation to the pressure in the crank chamber 12 a. If the pressure in the crank chamber 12 a increases, the inclination angle of the swash plate 18 decreases, thus reducing the compressor displacement. In contrast, if the pressure in the crank chamber 12 a decreases, the inclination angle of the swash plate 18 increases, thus raising the compressor displacement.

[0031] A control valve 25 is located in the rear housing member 13. The control valve 25 adjusts the amount of the refrigerant gas that flows from the discharge chamber 13 b to the crank chamber 12 a. The refrigerant gas in the crank chamber 12 a is supplied to the suction chamber 13 a through a bleeding passage 26 that has a restrictor. The pressure in the crank chamber 12 a is thus varied in relation to the amount of the refrigerant gas that flows from the crank chamber 12 a to the suction chamber 13 a through the bleeding passage 26, as well as the amount of the refrigerant gas that flows from the discharge chamber 13 b to the crank chamber 12 a, which is controlled by the control valve 25.

[0032] The suction chamber 13 a is connected to the discharge chamber 13 b through an external refrigerant circuit 27, which includes a first line 27 a and a second line 27 b. An oil separator 28 is located in the first line 27 a of the external refrigerant circuit 27. The oil separator 28 incorporates a separating cylinder. Refrigerant gas is introduced to the oil separator 28 and is circulated around the separating cylinder. This causes centrifugal force that acts to separate lubricant oil from refrigerant gas. The separated lubricant oil is collected in a lower portion of the separator 28, as viewed in a state in which the compressor is installed in the vehicle.

[0033] The through hole 12 b, which is formed in the front housing member 12, includes an oil chamber 29. A first seal mechanism 30 and a second seal mechanism 31 are located between the inner wall of the through hole 12 b and the outer side of the rotary shaft 14. The first seal mechanism 30 and the second seal mechanism 31 serve to seal the oil chamber 29 to prevent the refrigerant gas from leaking to the outside of the housing. The first seal mechanism 30 includes a seal ring 30 a that abuts against the inner wall of the through hole 12 b. A support ring 30 b supports the seal ring 30 a. The second seal mechanism 31 contacts a facing side of the support ring 30 b. The second seal mechanism 31 has a ring that rotates integrally with the rotary shaft 14.

[0034] A seal 32 is located between the second seal mechanism 31 and the first radial bearing 15. The seal 32 isolates the oil chamber 29 from the crank chamber 12 a. The material of the seal 32 is, for example, rubber or fluorine contained resin. The seal 32 is a ring type that has a substantially C-shaped cross-section. The seal 32 abuts against the inner wall of the through hole 12 b and the outer side of the rotary shaft 14. More specifically, the oil chamber 29 is formed by the first seal mechanism 30, the second seal mechanism 31, and the seal 32, which are located in the through hole 12 b. The seal 32 axially moves along the rotary shaft 14, and the movement is restricted by a step (not shown).

[0035] The oil chamber 29 has an inlet 29 a and an outlet 29 b. The inlet 29 a is connected to a supply passage 33. The supply passage 33 has an end that opens to the oil chamber 29. The outlet 29 b is connected to a discharge passage 34. The discharge passage 34 has an end that opens to the oil chamber 29. The supply passage 33 is connected to the lower end of the oil separator 28 through a first pipe 35. The discharge passage 34 is connected to the second line 27 b of the external refrigerant circuit 27 through a second pipe 36.

[0036] The operation of the compressor, which is configured as described above, will hereafter be described.

[0037] When the rotary shaft 14 is rotated, the swash plate 18 is rotated integrally with the rotary shaft 14 through the lug plate 17. The rotation of the swash plate 18 is converted to the reciprocation of each piston 20 through the associated shoes 21. Accordingly, refrigerant gas flows from the external refrigerant circuit 27 to the suction chamber 13 a. The refrigerant gas is then supplied to the compression chamber 11 b of each piston 20 through the associated suction port 22 a. When the piston 20 is moved from the bottom dead center to the top dead center, the refrigerant gas in the compression chamber 11 b is compressed to a predetermined pressure. The refrigerant gas is then discharged to the discharge chamber 13 b through the associated discharge port 22 b. Subsequently, the refrigerant gas is returned from the discharge chamber 13 b to the external refrigerant circuit 27 through a discharge line.

[0038] A controller (not shown) controls the opening size of the control valve 25 in relation to the cooling load required for the compressor. The amount of the refrigerant gas that flows from the discharge chamber 13 b to the crank chamber 12 a is thus altered. If the cooling load is relatively large, the amount of the refrigerant gas that flows from the discharge chamber 13 b to the crank chamber 12 a is decreased. This reduces the pressure in the crank chamber 12 a, thus inclining the swash plate 18 toward a maximum inclination angle. Accordingly, the stroke of each piston 20 is increased to raise the compressor displacement. In contrast, if the cooling load is relatively small, the amount of the refrigerant gas that flows from the discharge chamber 13 b to the crank chamber 12 a is increased. This raises the pressure in the crank chamber 12 a, thus inclining the swash plate 18 toward a minimum inclination angle. Accordingly, the stroke of each piston 20 is decreased to lower the compressor displacement.

[0039] The refrigerant gas that is returned from the discharge chamber 13 b to the external refrigerant circuit 27 passes through the oil separator 28. The oil separator 28 separates lubricant oil from the refrigerant gas. The refrigerant gas is then supplied to a condenser. The separated lubricant oil enters the supply passage 33 through the first pipe 35 and then flows to the oil chamber 29. The lubricant oil then enters the discharge passage 34 and flows to the second line 27 b of the external refrigerant circuit 27 through the second pipe 36.

[0040] The first embodiment has the following advantages.

[0041] The seal 32 isolates the oil chamber 29 from the crank chamber 12 a, thus preventing refrigerant gas from leaking from the crank chamber 12 a to the oil chamber 29. Accordingly, the pressure in the crank chamber 12 a is optimally adjusted to a preferred value. As a result, the inclination angle of the swash plate 18 is controlled accurately and smoothly.

[0042] The oil chamber 29 is sealed by the first seal mechanism 30, the second seal mechanism 31, and the seal 32. The oil chamber 29 is constantly supplied with lubricant oil, which is separated from refrigerant gas by the oil separator 28. Thus, lubricant oil is reliably supplied to the movable portions of the first and second seal mechanism 30, 31 and the seal 32. This structure increases lubrication of the first and second seal mechanism 30, 31 and the seal 32, thus prolonging their lives.

[0043] In the prior art, lubricant oil is supplied to the oil chamber in the form of mist, as dispersed in refrigerant gas. However, in this embodiment, the oil separator 28 separates lubricant oil from refrigerant gas. The separated lubricant oil is supplied to the oil chamber 29 in the form of liquid. This increases the amount of the lubricant oil supplied to the oil chamber 29, thus optimizing the lubrication of the first and second seal mechanisms 30, 31.

[0044] The seal 32 isolates the oil chamber 29 from the crank chamber 12 a. The pressure in the oil chamber 29 remains thus lower than the pressure in the crank chamber 12 a. This structure decreases the load that acts on the first and second seal mechanisms 30, 31, thus prolonging life of each seal mechanism 30, 31. Further, the refrigerant gas in the crank chamber 12 a, which is relatively hot, does not enter the oil chamber 29. Thus, the temperature in the oil chamber 29 does not rise. This improves durability of each seal mechanism 30, 31.

[0045] The outlet 29 b of the oil chamber 29 is located upward from the axis of the rotary shaft 14, when the compressor is installed in the vehicle. The lubricant oil that is retained in the oil chamber 29 thus constantly lubricates the rotary shaft 14. Accordingly, the first and second seal mechanisms 30, 31 are always sufficiently lubricated, and the durability of each seal mechanism 30, 31 is further improved.

[0046] If refrigerant gas leaks from the crank chamber 12 a to the oil chamber 29 through the seal 32, the leaked gas is introduced to the second pipe 36 through the discharge passage 34. This structure prevents the refrigerant gas from leaking to the exterior of the compressor. In other words, as long as the inclination angle of the swash plate 18 is reliably controlled in relation to the crank pressure, the seal 32, which isolates the crank chamber 12 a from the oil chamber 29, does not necessarily have to have an improved seal performance. It is thus possible to use a simply configured, inexpensive product as the seal 32.

[0047] If carbon dioxide is used as refrigerant in the compressor, pressure produced by the refrigerant in the compressor is ten or more times as high as pressure caused by chlorofluorocarbon in the compressor. Thus, in this case, the seal 32, which maintains the pressure in the oil chamber 29 at a relatively low level, is further advantageous.

[0048] The oil chamber 29 is connected to the oil separator 28 through the first pipe 35. The oil chamber 29 is also connected to the second line 27 b of the external refrigerant circuit 27 through the second pipe 36. The circuit in which lubricant oil flows is thus simply configured.

[0049] Since the oil separator 28 is located in the exterior of the compressor, it is easy to replace.

[0050] Next, a second embodiment of the present invention will be described with reference to FIG. 2. Same or like reference numerals are given to parts in FIG. 2 that are the same as or line corresponding parts in FIG. 1. The description of these parts is omitted. The second embodiment is different from the first embodiment in that the oil separator 28 is located in the interior of the compressor. The oil separator 28 is described in U.S. Pat No. 6,015,269 (corresponding to Japanese Unexamined Patent Publication No. 10-281060).

[0051] More specifically, as shown in FIG. 2, the oil separator 28 of the second embodiment is accommodated in the rear housing member 13. The oil separator 28 incorporates the oil separating cylinder 28 a. When refrigerant gas is circulated around the separating cylinder 28 a, lubricant oil is separated from the refrigerant gas. The refrigerant gas then flows from the oil separator 28 to the discharge chamber 13 b.

[0052] The oil separator 28 is connected to the inlet 29 a of the oil chamber 29 through a first passage 37 and the supply passage 33. The first passage 37 extends through the rear housing member 13, the cylinder block 11, and the front housing member 12. The supply passage 33 is formed in the front housing member 12. The outlet 29 b of the oil chamber 29 is connected to the suction chamber 13 a through a second passage 38 and the discharge passage 34. The second passage 38 extends through the rear housing member 13, the cylinder block 11, and the front housing member 12. The discharge passage 34 is formed in the front housing member 12.

[0053] The second embodiment has the following advantage, in addition to the advantages of the first embodiment.

[0054] In the second embodiment, the oil separator 28 is accommodated in the rear housing member 13. After the oil separator 28 separates lubricant oil from refrigerant gas, the lubricant oil enters the supply passage 33 through the first passage 37, thus flowing to the oil chamber 29. The lubricant oil then enters the discharge passage 34 and is returned to the suction chamber 13 a through the second passage 38. The passages 33, 34, 37, 38 are all formed in the wall of the compressor housing, which includes the front housing member 12, the cylinder block 11, and the rear housing member 13. It is thus unnecessary to locate any passages in the exterior of the compressor. Accordingly, the compressor is easy to handle.

[0055] A third embodiment of the present invention will hereafter be described with reference to FIG. 3. The second line 27 b, the first pipe 35, the supply passage 33, the discharge passage 34, the second pipe 36 and suction chamber 13 a form a suction pressure zone, or a low pressure zone, which is exposed to a relatively low pressure. The third embodiment is different from the first and second embodiments in that refrigerant gas is supplied from the suction pressure zone to the oil chamber 29 without separating lubricant oil from the refrigerant gas. The refrigerant gas is then returned to the suction pressure zone.

[0056] As shown in FIG. 3, an end of the first pipe 35 is connected to the second line 27 b of the external refrigerant circuit 27, and the other is connected to the supply passage 33. The first pipe 35 has a branch 35 a, and the branch 35 a is connected to the discharge passage 34 through the second pipe 36. The third embodiment thus has the following advantage, in addition to the advantage that leakage of refrigerant gas is sufficiently suppressed.

[0057] The refrigerant gas supplied from the suction pressure zone to the oil chamber 29 contains lubricant oil in the form of mist. The lubricant oil thus optimally lubricates the first and second seal mechanisms 30, 31. Further, the oil chamber 29 is constantly supplied with relatively cool refrigerant. This suppresses heating of the first and second seal mechanisms 30, 31, thus increasing the durability of each seal mechanism 30, 31.

[0058] Next, a fourth embodiment of the present invention will be described with reference to FIG. 4. The fourth embodiment is different from the first and second embodiments in that an accumulator 39, instead of the oil separator 28, is located in the external refrigerant circuit 27.

[0059] As shown in FIG. 4, the external refrigerant circuit 27 includes the first line 27 a, the second line 27 b which located at the upper stream side of the accumulator 39, and a third line 27 c which located at the lower stream side of the accumulator 39. The accumulator 39 is located in the external refrigerant circuit 27. The accumulator 39 prevents refrigerant liquid from entering the suction chamber 13 a. That is, the accumulator 39 separates refrigerant liquid and lubricant oil from refrigerant gas. The lubricant oil is then separated from the refrigerant liquid and is accumulated in a lower portion of the accumulator 39, as viewed in a state in which the compressor is installed in the vehicle. Meanwhile, some lubricant oil remains contained in refrigerant gas and is supplied to the suction chamber 13 a, together with the refrigerant gas. The lower portion of the accumulator 39 is connected to the supply passage 33 through the first pipe 35. The discharge passage 34 is connected to the third line 27 c of the external refrigerant circuit 27 through the second pipe 36.

[0060] The fourth embodiment has the following advantage, in addition to the advantages of the first embodiment.

[0061] The temperature of the lubricant oil separated from the refrigerant gas by the accumulator 39 is relatively low. Since the lubricant oil is supplied to the oil chamber 29, the movable portions of the first and second seal mechanisms 30, 31, which are located in the oil chamber 29, are sufficiently cooled. This sufficiently suppresses heating of the first and second seal mechanisms 30, 31.

[0062] A fifth embodiment of the present invention will hereafter be described with reference to FIG. 5. The fifth embodiment is different from the second embodiment in that a part of the refrigerant path is formed in the rotary shaft 14.

[0063] As shown in FIG. 5, the suction chamber 13 a is formed in the middle of the rear housing member 13. The discharge chamber 13 b is formed around the suction chamber 13 a and is located radially outward from the suction chamber 13 a. An accommodating recess 40 is formed in the cylinder block 11 and receives the rear end of the rotary shaft 14. The accommodating recess 40 is connected to the suction chamber 13 a through a communication hole 41 that extends through the valve plate assembly 50. A seal 42 is located between the inner wall of the accommodation recess 40 and the outer side of the rotary shaft 14.

[0064] A communication passage 43 is formed in the rotary shaft 14 and connects the accommodating recess 40 to the oil chamber 29. The communication passage 43 thus has an opening to the oil chamber 29. The opening corresponds to the inlet 29 a of the oil chamber 29. A lip seal 44 , or a seal mechanism, is located between the outer side of the front end of the rotary shaft 14 and the inner wall of the front housing member 12. In the fifth embodiment, some refrigerant flows from the suction chamber 13 a to the oil chamber 29 through the communication passage 43. The refrigerant then enters the discharge passage 34 and is returned to the suction chamber 13 a through a passage 38 that is formed in the wall of the compressor housing. That is, refrigerant circulates only in the compressor, and it is unnecessary to install a refrigerant passage in the exterior of the compressor.

[0065] It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Particularly, it should be understood that the invention may be embodied in the following forms.

[0066] The seal 32 does not necessarily have to be a ring type that has a C-shaped cross-sectional shape. For example, in a sixth embodiment shown in FIG. 6(a), the seal 32 is a ring type that has an L-shaped cross section. The seal 32 of this embodiment is formed of polytetrafluoroethylene (PTFE). Further, in a seventh embodiment shown in FIG. 6(b), the seal 32 is an oil seal type. Alternatively, in an eighth embodiment shown in FIG. 6(c), the seal 32 is a ring type that has a square-shaped cross section. Likewise, the seal 42, which is shown in FIG. 5, may be a ring type that has a C-shaped or square-shaped cross section. Alternatively, the seal 42 may be an oil seal type.

[0067] Further, a lip seal may be used in embodiments other than the fifth embodiment, which is shown in FIG. 5.

[0068] In the first, third, and fourth embodiments, the second pipe 36 may be replaced by the passage 38, which is formed in the wall of the compressor housing. In this case, refrigerant or lubricant oil is returned to the suction chamber 13 a through the passage 38. Alternatively, the second pipe 36 may be connected directly to the suction chamber 13 a, instead of being connected to the suction chamber 13 a through the second line 27 b of the external refrigerant circuit 27.

[0069] In the illustrated embodiments, the outlet 29 b of the oil chamber 29 is located in an upper section of the oil chamber 29, as viewed in a state in which the compressor is installed in the vehicle. However, the outlet 29 b may be located in a lower section of the oil chamber 29.

[0070] The seal 32 may be located between the radial bearing 15 and the crank chamber 12 a. In this case, the radial bearing 15 is located in the oil chamber 29 and is sufficiently lubricated.

[0071] The present invention may be applied to a fixed displacement type compressor.

[0072] The present invention may be applied to a wobble plate type compressor. In this compressor, a wobble plate, or a drive plate, is supported by a rotary shaft and rotates relative to the rotary shaft.

[0073] Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims. 

1. A compressor comprising: a housing, which has a suction pressure zone, and a crank chamber; a cylinder bore formed in the housing; a rotary shaft, which has a front end portion and a rear end portion, wherein the rotary shaft is supported by the housing such that the front end portion of the rotary shaft protrudes from the housing; a piston accommodated in the cylinder bore; a swash plate, which is accommodated in the crank chamber and is connected to the piston such that rotation of the rotary shaft is converted to reciprocation of the piston; an oil chamber located in the housing near the front end portion of the rotary shaft, wherein the oil chamber has an inlet and an outlet, wherein the outlet connects to the suction pressure zone, wherein either lubricant oil that is separated from refrigerant gas or refrigerant gas in the suction pressure zone flows into the oil chamber from the inlet and flows out from the outlet to the suction pressure zone; a seal mechanism for sealing the oil chamber; and a seal for sealing between the oil chamber and the crank chamber.
 2. The compressor according to claim 1, wherein the seal mechanism is located in the vicinity of the front end portion of the rotary shaft, wherein the seal is located between the seal mechanism and the crank chamber.
 3. The compressor according to claim 1, wherein the inclination of the swash plate is changed in accordance with the pressure of the crank chamber, and a stroke of the piston is changed.
 4. The compressor according to claim 1, wherein a pipe connects the outlet of the oil chamber to the suction pressure zone.
 5. The compressor according to claim 1 further being connected to an external refrigerant circuit, wherein the compressor has an oil separator, which separates lubricant oil from the refrigerant gas, wherein the oil separator is connected to the external refrigerant circuit.
 6. The compressor according to claim 5, wherein the oil separator is an accumulator, which separates refrigerant liquid and refrigerant gas.
 7. The compressor according to claim 1, wherein an oil separator is accommodated in the compressor, wherein the lubricant oil separated by the oil separator is introduced to the oil chamber through the inlet of the oil chamber.
 8. The compressor according to claim 1, wherein the outlet of the oil chamber is located above the axis of the rotary shaft.
 9. The compressor according to claim 1, wherein the seal is located in the periphery of the rotary shaft, wherein the seal has a C-shaped cross section.
 10. The compressor according to claim 1, wherein the seal has an L-shaped cross section.
 11. The compressor according to claim 1, wherein the seal has a square-shaped cross section.
 12. A compressor comprising: a housing, which has a suction pressure zone, and a crank chamber; a plurality of cylinder bores formed in the housing; a rotary shaft which has a front end portion and a rear end portion, wherein the rotary shaft is supported by the housing such that the front end portion of the rotary shaft protrudes from the housing; a piston accommodated in each of the cylinder bores; a swash plate, which is accommodated in the crank chamber and is connected to the piston such that rotation of the rotary shaft is converted to reciprocation of the piston, wherein the swash plate is supported by the rotary shaft to change the inclination of the swash plate and a stroke of the piston is changed; an oil chamber located in the housing near the front end portion of the rotary shaft, wherein the oil chamber has an inlet and an outlet, wherein the outlet connects to the suction pressure zone and is located above the axis of the rotary shaft, wherein either lubricant oil separated from refrigerant gas or refrigerant gas in the suction pressure zone flows in the oil chamber form the inlet and flows out from the outlet to the suction pressure zone; a seal mechanism for preventing the refrigerant gas from leaking to an outside of the housing, wherein the seal mechanism is located in the front end portion of the rotary shaft; and a seal for sealing between the oil chamber and the crank chamber, wherein the seal is located between the seal mechanism and the crank chamber.
 13. The compressor according to claim 12, wherein a pipe connects the outlet of the oil chamber to the suction pressure zone.
 14. The compressor according to claim 12 further being connected to an external refrigerant circuit, wherein the compressor has an oil separator, which separates lubricant oil from the refrigerant gas, wherein the oil separator is connected to the external refrigerant circuit.
 15. The compressor according to claim 14, wherein the oil separator is an accumulator, which separates refrigerant liquid and refrigerant gas.
 16. The compressor according to claim 12, wherein an oil separator is accommodated in the compressor, wherein the lubricant oil separated by the oil separator is introduced to the oil chamber through the inlet of the oil chamber.
 17. The compressor according to claim 12, wherein the seal is located in the periphery of the rotary shaft, wherein the seal has a C-shaped cross section.
 18. The compressor according to claim 12, wherein the seal has an L-shaped cross section.
 19. The compressor according to claim 12, wherein the seal has a square-shaped cross section. 